1. Outline - Lecture 9 [Nov. 18, 2003]
Ch. 10: Children with Visual Impairments
How the eye works
Definitions & terms
Causes of visual impairments
Effect of visual impairments on the child
Effect of visual impairments on the family
Educational implications
Ch. 12: Children with Neurological Disabilities
Definition & prevalence rates
The central nervous system

2. Structure of the Eye – see p. 365
Structure of eye is similar to that of a camera
3 layers of tissue:
1. Outer layer:
Sclera – thick, white fibrous covering
Cornea – first and most important refracting surface of the eye
2. Middle Layer:
Iris – colored speckled area, opens & closes according to light conditions
Lens – second refracting surface, transmits & further deflects light rays toward retina

3. Structure of the Eye – see p. 365
3. Inner Layer:
Retina – light-sensitive surface that records the image in an upside-down, back-to-front format
Macula - point of clearest vision, contains the Fovea – most sensitive spot on retina
Reflected rays of light from an object strike the eye.
These rays are refracted at the surfaces of the cornea and the lens.
This refraction yields a focused image on the retina.
The image is then transmitted via the optic nerve to the occipital lobe of the brain, where it is interpreted.

4. Development of Visual Skills
Newborn: focus on a human face & follow the movement of the face 90 degrees across a visual field
1 month: follow object horizontally 180 degrees
2 months: follow same object vertically
3 months: distinguish colours & follow an object in a complete circle
4 months: reach for & grab an object anywhere in the visual field
6 months: binocular vision is well developed
Visual acuity appears to be 20/600 at birth, 20/100 at 6 mo., 20/30 by 3 years and 20/20 by 5 years.

5. Definitions: Legal & Educational
Legal blindness: 20/200 or less in better eye with the best correction
Legal partial sight: not greater than 20/70 in the better eye after correction
Educational: focus on functional abilities
Low vision: severe visual impairment even after correction, will need vision aids & environmental modifications in school
Blind: either no vision or, at most, light perception; need to learn through non-visual means [Braille]

6. Causes of Vision Problems
Refraction errors:
Myopia; Hyperopia; Presbyopia; Astigmatism
Occular-motor problems:
Strabismus; Nystagmus
Amblyopia - visual pathway atrophies
Diseases:
Cataracts; Diabetic retinopathy; Glaucoma;
Retinopathy of prematurity [ROP];
Retinitis pigmentosa; Retinoblastoma

7. Vision Tests For infants: Ages 2-4 Ages 4-6 Older children
fixing and following
opticokinetic response
preferential looking tests
visual evoked responses
Allen Kindergarten Chart
Modified Snellen [Tumbling “E”]
Snellen eye chart

8. Effects of Visual Impairment:
on Motor development
Self-initiated mobility
Delayed fine & gross motor skills
Causes of delayed motor development:
parental overprotection; motivation; spatial abilities
on Perceptual development
Perceptual discrimination [texture, weight, sound discrimination] no better than sighted children
Tactile no better than sighted child until after age 11
Tactile defensiveness
SENSES MUST BE TRAINED TO COMPENSATE

9. Effects of Visual Impairment:
on Cognitive development
Same until about 4 months of age
Delayed concept development
Concepts formed tend to be less complex
Possible reasons for:
Visual impairment affects range and variety of experiences; the ability to explore; the ability to exert control over the environment & the self in relation to the environment

10. Effects of Visual Impairment:
on Language development
Babbling
Post-babbling
Early vocabulary
Later language use
no difference
articulation problems
Nelson’s categories hold
don’t use words creatively
don’t overextend
not as rich
use only in the context learned
focused on self
don’t tend to use language much

11. Mulford [1988]: Compared first 50 words of blind & sighted children
Sighted Blind
Specific nominals % 22%
General nominals % 38%
Action words % 24%
Modifiers % %
Personal-social % %
Function words % %
Both used mostly nominals but blind used more specific
Blind children used action words to describe own actions
Use of specific nominals linked to social-interaction function. Use of general nominals linked to cognitive function [grouping & classifyingconcept formation]

12. Effects of Visual Impairment:
on Social & emotional development
Infancy: -Delayed in self-sufficiency skills
-No separation anxiety until 2 years of age
Early years: -Lower social maturity
-Social cognitions impaired
Later years: -Locus of control often external BUT depends on whether individual is partially sighted or totally blind
Adjustment: -Early adjustment favoured residential schools
-Children in integrated settings showed better adjustment in adolescence & adulthood

13. Janson & Merenyi [1992]
Compared play of 3 to 6 yr.old congenitally blind children [N=8] with sighted peers [N=2] – over several play sessions with teacher present
Blind children
-more passive in play with peers
-ask for & respond to direction from peers
-show little spontaneous affect
-more responsive to teacher
-orient toward & try to interact more with teacher than peers

14. Effects of Visual Impairment
on the Family
Factors influencing parents’ attitudes:
Severity of the handicap
Age of onset of the visual impairment
How diagnosis was initially received
Support from professionals & educators
Daily routine
Social relationships
Parental involvement in school

15. Educational Issues Early assessment & intervention Listening skills
Reading skills
Braille
Low vision aids
use of special aids and equipment
Visual stimulation
Orientation and mobility training
Social & functional living skills
Vocation/career options
School placement

16. Technological Advances
Devices for:
Visual access to print
Auditory access to print
Tactile access to print
Independent travel

17. Ch. 12: Neurological Disabilities Definition & Prevalence Rates
Neurological impairments resulting from
damage or dysfunction of brain and/or
spinal cord.
Damage can occur
Prenatally: especially during 1st trimester
e.g. Fetal Alcohol Syndrome
Perinatally: e.g. anoxia
Postnatally: e.g. meningitis, encephalitis
Low incidence disabilities
.2 to 1.5% of the school age population

18. The Central Nervous System
Composition of the Brain & Spinal Cord
Neurons
Glial cells
Myelin
Brain
4 lobes
2 hemispheres
Corpus Callosum
Hemispheric dominance
Spinal Cord